As part of the organization Mithril, Sergeant Souske Sagara, Melissa Mao and Kurz Weber receive a secret mission: guarding Kaname Chidori, a popular student from a Tokyo high school who has hidden military potential.

Sousuke is set on his mission to protect Kaname, and attacks anything vaguely resembling a threat to Kaname. This leads to funny situations and Sousuke has to explain Kaname why he is following her, blaming coincidence.

Sousuke gets oriented in his Garbage Duty and Kurtz gets to know the targets a little better. Meanwhile Tessa takes care of a research center in Russia. Sousuke's team encounter a mysterious man climbing to Kaname's balcony.

The airplane with Sousuke, Kaname and 400 of their classmates is hijacked and brought to a secluded location. Kaname is taken away from the plane, but what will Sousuke do to rescue her?

Sousuke comes to Kaname's rescue, and the rest of the rescue team arrives on the scene as well, but can they hold off the army and save the students? Can Sousuke get Kaname to safety?

As the rescue team has left, Sousuke, Kaname and Kurz try to figure out a way to get back to safety.

Sousuke suddenly decides to become Mizuki’s boyfriend! The cold, watchful eyes of Mizuki's friends settle firmly on Sagara - but it’s Kaname’s reaction he should be worrying about.

When Tessa rushes to an SDF base after hearing that an A21 member has been captured, she’s shocked to find Takuma Kugayama. Seina, at the controls of an RK-92, has an even bigger surprise waiting.

Kaname, Sousuke, and the gang use summer break as an opportunity to visit the Narushino military festival, and during the annual AS competition, Sousuke helps give the underdog an advantage.